1. Field of the Invention
This invention generally relates to a bicycle hub. More specifically, the present invention relates to a rear bicycle hub constituting the hub for a rear wheel of a bicycle.
2. Background Information
A rear hub for a bicycle is provided with a hub spindle disposed at the center of rotation of the rear wheel; a hub shell installed rotatably about the hub spindle; and a freewheel disposed adjacently to the hub shell in the axial direction. Rotation of a sprocket, which is engaged with a chain, is delivered to the hub shell by the freewheel. There is known in the prior art a rear hub for a bicycle in which a driving force measuring part capable of measuring driving force of a rider is disposed between the freewheel and the hub shell (see U.S. Pat. No. 6,418,797, for example).
The prior art rear hub for a bicycle has a coupling member for coupling the freewheel and the hub shell. The coupling member is formed to a hollow cylindrical shape, and the sprocket is installed on one end part thereof, while the other end part is coupled to the hub shell. The coupling member is provided with a strain gauge for detecting twisting of a coupling part thereof, and detects the amount of twist of the coupling part. Driving force of a rider is measured from the amount of twist measured thereby.